Subject: Re: Lead shot
Date: Jul 18 17:58:35 1995
From: Jon Anderson - anderjda at dfw.wa.gov


On Tue, 18 Jul 1995, Don Baccus wrote:

> I know nothing of lead pickup by aquatic plants, but assume the
> folks studying the phenomena of lead poisoning in waterfowl have
> looked at this, as it is an obvious concern since this is what
> most of the ducky-poos are eating. Aquatic plants are less dependent
> on their root system for nutrient pickup (indeed, in many the roots
> are really just anchors) than those on land so it might not be as bad
> as you'd think.

Don,

The problem with lead shot, sinkers, etc in the waters and fields which
lead to the Feds outlawing lead duck shot was not with the uptake of the
metal by plants and the birds feeding on the plants.

The problem with the lead is when the duck/goose/swan is feeding and
picks up the lead pellet/weight. Waterfowl use gravel to grind their
food, and even the grass-grazers (Canada geese, wigeon, etc) will have a
crop full of gravel. When the bird mistakes a pellet for a seed or for a
bit of gravel, the pellet goes into the crop where it is assaulted by the
friction of the other gravel and by the crop's digestive juices - the
lead of the pellet is taken in solution into the bird's digestive tract.

The levels of lead in the blood can be extremely high from just a few
ingested pellets. The literatue of 10-15 years ago abounds with lab
studies of how many pellets it takes to get a Mallard sick with lead
poisoning.

I understand that some areas that have been hunted over for the last 200
years have some pretty high soil levels of lead. But, I would be
extremely surprised if there was enough lead uptake by plants to "poison"
waterfowl. If livestock were fed continuously on a diet of nothing BUT
forage from a contaminated site, I might expect to see some lead in the
stock, but not to the point that one sees in lead-poisoned waterfowl.

Again, do any EPA-DOEcology types have any info to enlighten us?

Jon. Anderson
Olympia, WA
anderjda at dfw.wa.gov